The most commonly employed processes for purifying a protein, e.g., a monoclonal antibody typically employ an engineered cell line (e.g., a CHO cell line) capable of secreting the protein into the cell culture media. The media or cell culture feed containing the protein of interest is then subjected to a series of purification steps to separate the protein from various impurities, e.g., cells, cell debris, DNA, host cell proteins etc.
A typical purification process usually entails subjecting the cell culture feed or media containing the protein to a clarification step followed by subjecting the clarified cell culture feed to an antibody capture step (e.g., a Protein A affinity chromatography step), followed by a cation exchange bind/elute chromatography step and/or an anion exchange chromatography step.
While the various steps in the purification process are designed to remove impurities in the cell culture feed containing the protein, fragments of the protein which are undesirable, are typically difficult to remove as they share many of the same properties as the intact protein.
Activated carbon has previously been used in air filters (see, e.g., U.S. Pat. No. 6,413,303), gas purification (see, e.g., U.S. Pat. No. 7,918,923), decaffeination (see, e.g., U.S. Pat. No. 4,481,223), gold purification (see, e.g., U.S. Pat. No. 5,019,162), fuel purification (see, e.g., U.S. Publication No. 2006/0223705 A1), hemoperfusion (see, e.g., U.S. Pat. No. 4,048,064), treatment of poisonings and overdoses (see, e.g., U.S. Pat. No. 4,453,929), sewage treatment (see, e.g., U.S. Pat. No. 8,329,035), spill cleanup (see. e.g., U.S. Pat. No. 4,770,715), groundwater remediation (see, e.g., U.S. Pat. No. 6,116,816), capture of volatile organic compounds from automobile fuel systems (see, e.g., U.S. Pat. No. 7,044,112), chemical purification (see, e.g., U.S. Pat. No. 4,906,445), distilled alcoholic beverage purification (see. e.g., U.S. Publication No. US 2007/0248730 A1), decolorization of sugar (see, e.g., U.S. Pat. No. 2,082,425), respirators (see, e.g., U.S. Pat. No. 5,714,126), gas masks (see, e.g., U.S. Pat. No. 4,992,084), protective chemical warfare suits (see, e.g., U.S. Pat. No. 7,877,819), and water purification processes (see, e.g., U.S. Pat. No. 7,537,695).
In addition, activated carbon has been used to remove small molecule impurities, such as fatty acids and bilirubin, from serum albumin (see. e.g., Chen et al., J. Biol. Chem., 242: 173-181 (1967); Nakano el al., Anal Biochem., 129: 64-71 (1983); Nikolaev et al., Int. J. Art. Org., 14:179-185 (1991)). Activated carbon has also been used to remove pigments as well as host proteins, proteases, and ribonucleases during the purification of plant viruses (see, e.g., Price, Am. J. Botany, 33: 45-54 (1946); Corbett, Virology, 15:8-15 (1961); McLeana et al., Virology, 31: 585-591 (1967), U.S. Publication No. US 2006/0281075 A1). Additionally, activated carbon has also been described as being useful for removal of lower molecular weight plasmid fragments from plasmid DNA. See, Kim et al., J. Biosci. Bioeng. 110:608-613 (2010).
Further, U.S. patent application Ser. No. 13/565,463, filing date Aug. 2, 2012, incorporated by reference herein in its entirety, describes the use of activated carbon in combination with other media for removal of proteinaceous impurities (e.g., host cell proteins) and DNA from a sample containing a biomolecule of interest (e.g., an antibody).
Lastly, U.S. Provisional Patent Application Ser. No. 61/769,269, filing date Feb. 26, 2013, incorporated by reference herein, describes the use of activated carbon for the selective removal of a protein from a mixture of proteins by changing solution conditions.